Efficacy of 1 alpha hydroxyvitamin D3 in the prevention of bovine parturient paresis

One hundred and seventeen Israeli-Friesian cows from herds with a milk fever incidence of more than 15 per cent were injected intramuscularly with either 350 micrograms 1 alpha hydroxyvitamin D3 (1 alpha OHD3) in propylene glycol or with the vehicle alone, close to calving. If parturition had not occurred within 72 hours a second injection was administered; parturition was induced two days after the second injection if necessary. There were 10 cases of milk fever among 57 control cows as opposed to two cases among the 60 animals treated with 1 alpha OHD3. In an attempt to prolong the effect of the drug, Israeli-Friesian cows were injected intramuscularly with 350 micrograms 1 alpha OHD3 in either 10 ml propylene glycol or arachis oil. 1 alpha OHD3 in arachis oil did not prolong the effect of the drug. 1 alpha OHD3 in propylene glycol increased plasma calcium concentrations more rapidly than when the drug was administered in oil. Additional cows of the same breed and age were injected intramuscularly with 350 micrograms 1 alpha OHD3 in propylene glycol. Five of the animals received a second dose four days, and five received a second dose five days after the first injection. Five animals served as uninjected controls. The plasma calcium levels of the injected cows were significantly higher (P less than 0.01) than those of the controls from the second until the 14th day after the first injection. Based on these results 451 Israeli-Friesian cows from herds with a milk fever incidence of more than 15 per cent were injected intramuscularly with 1 alpha OHD3 close to calving.(ABSTRACT TRUNCATED AT 250 WORDS)     

The prophylactic use of vitamin D3 in parturient paresis in the cow in a practice district in eastern Norway. A retrospective investigation.

The prophylactic effect in parturient paresis of an intramuscular injection of 10 million i.u. vitamin D3 one week prior to the expected calving date, was investigated in 84 cows which had previously suffered from parturient paresis. Clinical observations in connection with the development of parturient paresis after injection of vitamin D3 were compared with corresponding observations made on cows within the same population at the previous calving when no vitamin D3 was administered. The incidence of clinical parturient paresis in cows given vitamin D3 was 44.3 per cent. There were no significant differences in the incidence of parturient paresis in cows injected with vitamin D3 during the periods less than 2, 2--4, 5--8 and greater than 8 days before parturition. Average plasma calcium levels (mg/100 ml) before first calcium treatment, results of treatment, and the incidence of retained placenta in vitamin D3 injected cows did not differ significantly from corresponding data for cows with clinical parturient paresis which had not been given vitamin D3 before calving. It is concluded that vitamin D3 does not have any prophylactic effect in parturient paresis in cows in Eastern Norway.     

Plasma mineral and energy metabolite concentrations in dairy cows fed an anionic prepartum diet that did or did not have retained fetal membranes after parturition

OBJECTIVE: To compare plasma total calcium, phosphorus, magnesium, nonesterified fatty acids (NEFA), beta hydroxy butyrate (BHB), and glucose concentrations in parturient dairy cows that were fed an anionic prepartum diet between those with and without retained fetal membranes (RFM) at 24 hours after parturition. ANIMALS: 152 Holstein cows that calved during October through December of 1997 PROCEDURE: All cows were fed an anionic prepartum diet. Blood sample was taken within 6 hours after parturition from randomly selected cows. Thirty-nine cows had a diagnosis of RFM at 24 hours after parturition; 113 were not affected with RFM. At calving, body condition score (BCS; 1 [thin] to 5 [obese]), parity, and calving difficulty score were recorded. Plasma calcium, phosphorus, magnesium, NEFA, BHB, and glucose concentrations were compared between cows with or without RFM. RESULTS: Cows with RFM had significantly lower plasma calcium concentration soon after calving, compared with cows without RFM. Cows with a parity of > or = 3 had significantly lower plasma concentrations of calcium and higher concentrations of magnesium, compared with cows with a parity of 1 or 2. Cows with a BCS of > or = 3.25 at calving had significantly higher plasma concentrations of BHB than cows with a BCS of 2.75 to 3.0. Cows with dystocia had significantly higher plasma concentrations of glucose, compared with cows without dystocia. CONCLUSIONS AND CLINICAL RELEVANCE: In parturient cows fed a prepartum anionic diet, those with RFM have lower plasma calcium concentrations than cows without RFM, although this association does not prove a cause-effect relationship.     

Efficacy of oral calcium and/or sodium phosphate in the prevention of parturient paresis in cows

The goal of this study was to investigate the efficacy of calcium chloride, sodium phosphate or a combination of these two substances administered orally immediately postpartum for the prevention of parturient paresis in cows. Thirty-two cows that had had parturient paresis at the previous calving, and in which serum biochemistry had shown hypocalcaemia and hypophosphataemia, were used in the study. The cows were transferred to the Department of Farm Animals, University of Zurich, five days before their expected due dates. On a randomized trial, the cows were given calcium chloride, sodium phosphate, both substances or no treatment (controls) via a stomach tube immediately postpartum and 12 hours later. The cows were monitored for 96 hours during which time blood was collected on a regular basis for the determination of total calcium, ionized calcium, inorganic phosphorus and magnesium concentrations. Of the 32 cows treated, 19 (59%) had parturient paresis and 13 (41%) did not. The incidence of parturient paresis did not differ significantly among the groups although there was a tendency for a lower incidence in cows treated with both calcium chloride and sodium phosphate. The various treatments had no apparent effect on serum calcium concentration. The concentration of inorganic phosphorus increased significantly in cows treated with sodium phosphate compared with the controls. The results of this study showed that cows treated with both calcium chloride and sodium phosphate orally tended to have a lower incidence of parturient paresis. Further investigation into multiple administrations of oral calcium chloride and sodium phosphate, started before parturition, for the prevention of parturient paresis is required.     

Effects of long-term dietary supplementation with clinoptilolite on incidence of parturient paresis and serum concentrations of total calcium, phosphate, magnesium, potassium, and sodium in dairy cows

OBJECTIVE: To determine whether dietary supplementation with clinoptilolite affects the incidence of parturient paresis and serum concentrations of total calcium (tCa), inorganic phosphorus (PO(4) (2)), magnesium (Mg2+), potassium (K+), and sodium (Na+) in dairy cattle. ANIMALS: 52 dairy cows. Procedure-Cows were placed into 3 groups. The first 2 groups (group A [n = 17] and group B [17]) were offered a concentrate supplemented with 1.25% and 2.5% clinoptilolite, respectively. The third (group C [n = 18]) served as a control and was offered the concentrate alone. The experiment started 1 month before parturition and lasted until the beginning of the next nonlactating period. Around the time of calving, all cows were monitored for the development of parturient paresis. Blood samples were taken at the commencement of the experiment, on the day of calving, and thereafter at monthly intervals to measure serum tCa, PO(4) (2), Mg2+, K+, and Na+ concentrations. Results-The incidence of parturient paresis in group B cows was significantly lower, compared with group C cows. However, serum concentrations of tCa, P(O4) (2), Mg2+, K+, and Na+ were not significantly affected by long-term supplementation with clinoptilolite. CONCLUSIONS AND CLINICAL RELEVANCE: In the context of this experiment, clinoptilolite supplementation at 2.5% appeared to have reduced the incidence of parturient paresis in dairy cows, suggesting that its effectiveness depends on the amount incorporated in the ration of cows. Addition of clinoptilolite in the concentrate of dairy cows during the nonlactating period could be used as a cost-effective preventive treatment for parturient paresis.     

Lipid mobilization in parturient cows.

The blood levels of calcium, inorganic phosphorus, magnesium, glucose and NEFA were studied in cows at the time around partus. Eight of 16 cows developed hypocalcaemic paresis. Besides hypocalcaemia the paretic cows showed lower levels of inorganic phosphorus and higher levels of glucose and NEFA than non-paretic cows 24 hrs. post partum. It is known that lipolysis is associated with uptake of calcium in adipose tissue. The calcium content in perirenal adipose tissue was however lower in paretic cows than in non-paretic parturient cows and lactating cows slaughtered 3–5 months after calving. The calcium content in omental adipose tissue was about the same in all 3 groups. Despite increased lipolysis the calcium content in adipose tissue is thus not increased in cows suffering from parturient paresis.     

Studies on parturient paresis in dairy cows. V. On the composition and calcium binding capacity of two bovine serum protein fractions, with special regard to parturient paresis

In healthy cows unaffected by imminent or recent calving the protein in serum can directly bind the overwhelming proportion of the bound calcium. In recent calvers this capacity is considerably less. When adding ammonium sulphate to blood serum to 62 % of total saturation a protein fraction precipitates which is mainly albumin. This fraction has a far greater calcium binding capacity than the soluble fraction, which contains most of the serum globulin, and the lowering of this capacity after calving is entirely referable to the former fraction. No difference has been found in these respects between normal cows after calving and cows with parturient paresis.An analysis of 10 amino acids in the two protein fractions described above showed that the amino acid composition of both exhibits differences between recent calvers and cows outside the calving period, and likewise that each of the two fractions differs in composition between healthy cows after calving and cows with parturient paresis.     

The effect of oral calcium lactate in postpartum cows

The oral administration of calcium lactate for prophylaxis of bovine parturient paresis has been promoted for a number of years. The goal of the present study was to investigate the effect of this treatment on the serum concentrations of calcium, inorganic phosphorus and magnesium in parturient cows. Five fresh calved cows were given a drench containing calcium lactate and 5 control cows received the same drench but without calcium lactate. There were no significant differences in the serum concentrations of total and ionised calcium and magnesium between treated and control cows within 24 hours of treatment. Because the calcium lactate drench did not significantly affect calcium concentrations in the blood of fresh cows, it appears highly questionable whether the administration of calcium lactate decreases the risk of bovine parturient paresis. Based on our results, the oral administration of calcium lactate can not be recommended for prophylaxis of bovine parturient paresis.     

Estrone and Progesterone Plasma Levels of Normal Cows and Cows with Parturient Paresis

Blood plasma concentrations of estrone and progesterone, calcium and inorganic phosphorus were measured in 22 cows (Swedish Red and White Breed) from 4 weeks prepartum up to 6 days post partum. Ten cows with parturient paresis had Ca levels below 6 mg/100 ml. Data from plasma analyses in individual cows were grouped in the following periods: 28–22, 21–15, 14–8, 7–6, 5–4, 3, 2, 1 day(s) before parturition and 1, 2, 3–6 days after parturition. Statistical comparisons of the levels of the hormones and the ratio progesterone/estrone did not reveal any significant differences between the paretic and normal cows at any time period. The results do not support the theories that high systemic levels of estrogens or an imbalance between estrogen and progesterone predispose towards parturient paresis.     

Effect of intravenous calcium and oral sodium phosphate in cows with parturient paresis

The goal of this study was to determine whether oral administration of sodium phosphate in conjunction with intravenous calcium is more efficaceous than intravenous calcium alone for the treatment of parturient paresis. Thirty cows with parturient paresis were examined and treated by the same veterinarian. The cows were divided randomly into two groups of 15 cows each. Cows in group A received 500 ml of a 40 per cent calcium borogluconate solution containing 15.65 g calcium gluconate and borogluconate, with a supplement of 6 per cent magnesium hypophosphite (9.85 g magnesium hypophosphite) intravenously over a period of approximately 15 min. Cows in group B received the same treatment as well as 350 g of monobasic sodium phosphate (70 g inorganic phosphate, NaH2PO4 2 H2O, Streuli) dissolved in 0.5 litres of distilled water orally via a stomach tube. After treatment, the heart rate, respiratory rate, rectal temperature, superficial body temperature, rumen motility, appetite and defecation of the cows were monitored every hour for eight h. The cows' attempts to rise and their ability to stand were also noted. Initially, the results of clinical examination and serum electrolyte analyses did not differ between the two groups of cows.Within one hour of treatment, stupor was not observed in any of the cows. The general demeanour after treatment did not differ significantly between the two groups. In both groups, the average rectal temperature increased within two hours of the initiation of treatment, from 38.0 +/- 0.95 degrees C to 38.5 +/- 0.40 degrees C. There was no significant difference in the recovery rate between the groups. Of the 30 cows, 22 (73.3 per cent) stood within eight hours of treatment (10 cows from group A and 12 cows from group B). The type of treatment did not affect the time required to stand: cows in group A stood within 47.3 +/- 44 minutes and cows in group B stood within 24.2 +/- 32 minutes after the start of treatment. Our findings do not support the hypothesis that oral treatment with 350 g of sodium phosphate together with intravenous infusion of calcium in cows with parturient paresis results in an improved outcome, even though all the cows had hypophosphataemia as well as hypocalcaemia.     

An epidemiological and genetic study on registered diseases in Finnish Ayrshire cattle. III. Metabolic diseases

The epidemiology of clinical ketosis, hypocalcaemia and hypomagnesaemia was examined. In addition, the genetic variability of ketosis and parturient paresis was investigated. The data set consisted of the lactation records of 70,775 Finnish Ayrshire dairy cows. Each cow was under observation for 2 days before and for 305 days after calving. Lactation incidence rates (%) were: ketosis 6.0, parturient paresis 3.8, non-parturient paresis 0.6, hypomagnesaemic tetany, outdoor 0.6, and indoor 0.2. These diseases formed 22 % of all first treatments by veterinarians during farm visits. 92 % of the cases of ketosis occurred with 8 weeks of parturition, with the highest occurrence 3–5 weeks after calving. Four % of cases of parturient paresis occurred before, and 45 % within 24 h after calving. When cases were categorized by month of calving the risk of ketosis was higher during indoor feeding (October-April) than during outdoor feeding (May-September). The risk of parturient paresis did not significantly vary with month of calving. The occurrence of ketosis increased with parity up to the 4th and decreased thereafter. The occurrence of parturient paresis increased with parity. Both the increase in herd milk yield and the increase in individual milk yields were positively associated with the occurrence of ketosis and parturient paresis. The cows with a history of the reproductive tract infection had a higher risk of contracting ketosis. Heritability estimates for ketosis in various parity groups were from 1.6 % to 4.1 % on the binomial scale (corresponding to 7.3 %–14.4 % on the normal scale), and for parturient paresis from 3.5 to 10.5% (corresponding from 18.3 % to 27.4 %). The genetic correlation between ketosis and parturient paresis, and these and current milk production for all material were insignificant.     

Parturient paresis and hypocalcemia in ruminant livestock

Parturient paresis (hypocalcemia) is most likely to affect dairy cattle around the time of parturition. It causes progressive neuromuscular dysfunction and flaccid paralysis. Older dairy cows, cows with a history of parturient paresis during a previous lactation, high-producing cows, and cows from the Jersey and Guernsey breeds are at highest risk for developing parturient paresis. Nonparturient hypocalcemia may also occur and is related to events other than parturition, such as severe stress, that temporarily overwhelm the mechanisms of calcium homeostasis. Beef cattle, sheep, and goats are affected less frequently by hypocalcemia than are dairy cows. Because these species are not as stressed for milk production as dairy cattle, nonparturient hypocalcemia makes up a higher proportion of cases in nondairy ruminants. Clinical signs of hypocalcemia in beef cattle, sheep, and goats tend toward hyperesthesia and tetany rather than the classic flaccid paralysis that occurs in dairy cattle with parturient hypocalcemia. Prompt and effective treatment of hypocalcemia helps to reduce the incidence of secondary complications, such as muscle damage or mastitis. The standard treatment regimen of 500 ml of 23 per cent calcium gluconate, administered intravenously, will elicit a favorable response in approximately 75 per cent of recumbent cows within 2 hours of treatment. Relapses following successful initial therapy are common and may be prevented in part by supplementation of intravenous treatment with an additional 500 ml of 23 per cent calcium gluconate administered subcutaneously. Proper nursing care following treatment speeds recovery and reduces the incidence of secondary complications owing to hypocalcemia.     

Treatment of parturient paresis with high-dose calcium

The goal of the present study was to evaluate a calcium dose that was higher than the conventional dose for treatment of parturient paresis in cows. Thirty cows with parturient paresis received 1000 ml of 40 per cent calcium borogluconate solution supplemented with 6 per cent magnesium hypophosphite. Cows in group A received 200 ml of the solution intravenously over a 10-minute period, and the remaining 800 ml via a slow intravenous drip over a six-hour period. Cows in group B received 500 ml of the solution intravenously over a 20-minute period, and the remaining 500 ml via a slow intravenous drip over a six-hour period. Afterwards, the cows were monitored continuously and examined every hour for eight hours. Samples of blood were collected from all the cows before treatment and at 10, 20, 40, 60, 90, 120, 180, 240, 300, 360, 420 and 480 minutes and 24, 48 and 72 hours after treatment. The concentrations of total calcium, ionised calcium, inorganic phosphorus and magnesium were determined. Cows that did not stand within 12 hours of treatment received one or more additional treatments. There was no significant difference in the recovery rate between the two groups. Of the 30 cows, 14 (47 per cent) rised after one treatment and 15 others (50 per cent) were cured after two or more treatments. One cow did not respond to repeated treatments and was euthanased four days after the start of treatment. The results of electrolyte analyses before treatment did not differ significantly between the two groups. In 27 (90 per cent) cows, the concentrations of calcium and inorganic phosphorus were lower than normal and in 3 (10 per cent) cows, only the concentration of inorganic phosphorus was lower than normal.The concentration of total calcium increased markedly ten minutes after the start of treatment in both groups, and at eight hours, the mean concentration of calcium was within the normal range. At 24 and 48 hours, the mean concentration of calcium was below normal, but at 72 hours it was again within the normal range. The concentration of inorganic phosphorus increased slowly in both groups, although it was not within the normal range at eight hours. In both groups, it achieved normal values at 24, 48 and 72 hours.The mean electrolyte concentrations did not differ significantly at any measuring point between cows that stood within eight hours of treatment and those that did not. Our results indicate that increasing the dose of calcium administered does not improve the recovery rate of cows with parturient paresis.     

Prolactin, estradiol, and progesterone changes in paretic and nonparetic cows during the periparturient period

We studied the relationship of serum prolactin, estradiol-17 beta, and progesterone concentrations to plasma calcium, phosphorus, and free hydroxyproline concentrations, as well as to dry matter intake, in 14 aged dairy cows (mean of 4.5 parities), 7 of which became paretic, from 28 days before to 4 days after calving. Plasma calcium and phosphorus concentrations and dry matter intake decreased more at parturition in paretic cows than in nonparetic cows. Prolactin concentrations were not different between paretic and nonparetic cows, but were variable. Concentrations of estradiol were higher in paretic cows from 15 to 5 days before parturition, whereas hydroxyproline concentration was lower in paretic cows on days 10 through 3 before parturition. Progesterone concentration was lower in paretic cows and decreased earlier at parturition, compared with that in nonparetic cows. The findings suggested that high estradiol concentrations in late pregnancy inhibit bone resorption and predispose aged cows to parturient paresis. The earlier decrease in progesterone concentration at parturition and lower concentrations throughout late pregnancy might have contributed to the greater inappetence in paretic cows at parturition. The importance of prolactin in the pathogenesis of parturient paresis is not clear.     

Effect of parity number on the dry matter intake of dairy cows during the first week after calving

We investigated the effect of parity number on the dry matter intake (DMI) of cows during the first week after calving. Eighty‐three cows were evaluated from 14 days before to 7 days after calving. DMI and milk yield were measured for 7 days after calving, and the calving score was measured. Blood samples were collected throughout the experiment. The average DMI during the first week after calving was reduced in the first‐lactation heifers and high‐parity number cows. A quadratic relationship between the parity number and the DMI was observed. The first‐lactation heifers had lower prepartum serum total protein (TP) concentration and milk yield, higher prepartum serum nonesterified fatty acid (NEFA) concentration and calving score than the multiparous cows. The recovery rate of serum calcium (Ca) after calving was slow in the cows in the parity 6. The DMI was positively affected by the serum Ca concentration after calving, milk yield, and prepartum serum TP concentration and was negatively affected by the calving score and prepartum serum NEFA concentration. We conclude that the DMI immediately after calving tends to be lower in first‐lactation heifers and high‐parity number cows, but factors that reduce the DMI differ according to parity number.     

Interaction between the levels of hormones and minerals in sera of healthy and sick cows

An interaction between blood levels of parathyroid hormone, calcitonin, 1.25-dihydroxycholecalciferol and levels of calcium, phosphorus and magnesium was examined in 85 cows, which included healthy cows and cows with ostemalacia, mastitis and paresis. Levels of parathyroid hormone (PTH) and calcitonin were determined in vitro using IMMULITE analyser (Diagnostic Products Corporation, USA), by means of immunometric assay. Levels of vitamin D were measured using the enzyme linked immunosorbent assay (ELISA). Levels of calcium, phosphorus and magnesium were determined using the automated Eos-Bravo analyser (Hospitex Diagnostics, Italy) with HOSPITEX reagents. The lowest blood levels of calcium (1.38 +/- 0.18 mmol/L) and phosphorus (0.65 +/- 0.12 mmol/L) were found in cows with parturient paresis. Decreased blood levels of phosphorus and magnesium were also determined in cows with osteomalacia. For cows with parturient paresis, which received a mineral supplement, the average serum level of calcium was by 20.7% higher than the level found in those which did not receive a supplement, and the level of phosphorus was by 23.6% higher, however, these levels remained low. The blood level of parathyroid hormone ranged from 3.47 to 5.20 pmol/L in healthy cows and from 3.95 to 15.21 pmol/L in sick cows. The highest and statistically significant increase in blood PTH level (up to 18.31 +/- 1.88 pmol/L) was found in cows with parturient paresis. The blood level of PTH correlated inversely with the level of calcium in cows with osteomaliacia (r = -0.89) and in cows with parturient paresis (r = -0.49 and r = -0.61, respectively). The serum level of calcitonin ranged from 1.46 pmol/L to 2.40 pmol/L in healthy and sick cows and the difference was not statistically significant. Lower serum levels of vitamin D were found in heifers-in-calf and in cows with mastitis. A clear correlation between levels of calcitonin, vitamin D and macronutrients was not found.     

Physiologic effects of administration of interleukin 1 beta in cows.

The immunomodulating polypeptide interleukin 1 beta (IL-1 beta) has been shown to be homologous to osteoclast-activating factor and is capable of stimulating increased osteoclastic bone resorption. This effect prompted an investigation into the potential use of IL-1 beta for prevention of parturient paresis, a disease of dairy cows characterized by hypocalcemia and poor osteoclastic resorption of bone. Six nonpregnant cows were treated with a high dosage of IL-1 beta (166 ng/kg of body weight) every 8 hours for 4 days. The IL-1 beta treatment significantly (P < 0.05) increased urinary hydroxyproline excretion, an index of osteoclast activity, indicating that bone calcium resorption might be stimulated by IL-1 beta treatment of cows. However, IL-1 beta treatment also caused transient fever, inappetence, increased pulse and respiratory rate, and diuresis. The acute, but transient, effect of IL-1 beta treatment was to cause a decrease in plasma calcium and phosphorus concentrations. The pleiotropic effects of IL-1 beta administration negated the positive effects on osteoclastic bone resorption, and indicates that this cytokine may be of minimal benefit for prevention of parturient paresis.     

Use of pre-partum urine pH to predict the risk of milk fever in dairy cows

The objective of this study was to evaluate the correlation between serum calcium (Ca) and inorganic phosphorus (IP) values and urine pH of cows fed common rations without the addition of anionic salts in late pregnancy. One hundred and seven Holstein cows, having completed two or more lactations and with an expected calving date within the next seven days were selected from two herds. In order to determine levels of serum Ca and IP and urine pH, blood and urine samples were collected seven to one days before parturition. Of the 107 sampled cows, 17 developed recumbency after calving and were considered to be affected by milk fever. There were significant ( p<0.01 ) negative correlations between urine pH and serum Ca, IP and the ratio of Ca to IP, The urine pH, and levels of serum Ca and IP measured within 48 h prior to parturition differed significantly ( p<0.001 ) between recumbent and non-recumbent cows. The sensitivity, specificity, positive and negative predictive values of urine pH test 48 h prior to parturition, using a cut off level of above pH 8.25, were 100%, 81%, 55%, and 100%, respectively. These signify that monitoring urine pH within 48 h prior to parturition is a sensitive method to assess the risk of parturient paresis. The results of this study emphasize the importance of acid-base status of the animal in the pathophysiology of milk fever.     

Plasma 1,25-dihydroxyvitamin D, insulin-like growth factor-1, calcium, magnesium and phosphorus concentrations in pregnant beef cows and calves from a herd with a known history of congenital joint laxity and dwarfism.

An investigation was undertaken to ascertain the possibility of a relationship between calcium, inorganic phosphorus, magnesium, 1,25-dihydroxyvitamin D [1,25(OH)2D], and insulin-like growth factor-1 (IGF-1) concentrations in blood plasma and occurrence of congenital joint laxity and dwarfism (CJLD) in young cattle. Pregnant cows were fed hay (30 cows) or grass silage (122 cows) during winter months (October 15 to calving in March). Blood samples were taken from cows on seven occasions during the experiment and 48 hours after calving, and from calves at birth, and at seven, 14 and 56 days old. Five per cent of calves born (six of 122) to cows fed grass silage and none born to cows fed hay were affected by CJLD. The diet and health status of calves were not significantly (P greater than 0.05) associated with the plasma concentration of 1,25(OH)2D. The plasma calcium concentration declined with age of the calves (P less than 0.05) but was not affected by the occurrence of CJLD. Plasma phosphorus and magnesium concentrations in calves born to cows fed silage were higher (P less than 0.05) than in those born to cows fed hay. At birth and seven days old, plasma phosphorus concentrations were higher (P less than 0.05) in CJLD-affected calves than in healthy calves but the plasma concentration of IGF-1 was not different (P greater than 0.05). It was concluded that the high plasma phosphorus concentrations in CJLD-affected calves and their dams could be related to the aetiology of the CJLD condition in calves.     

过瘤胃维生素D预防围产期奶牛低血钙症的效果

本试验选取围产期经产健康荷斯坦奶牛40头,随机分为4组:T1,T2,T3和C组,每组各10头.产前7d分别每头每天饲喂过瘤胃维生素D 1.5,3.0,6.0和0g,直至分娩,产后均不饲喂过瘤胃维生素D,试验至产后7d结束.所有试验奶牛在产前7d,3d、产后3d,7d及分娩当天测定血浆钙(Ca).磷(P)、碱性磷酸酶(A...